It is demonstrated that the nerve growth factor (hereinafter referred to as "NGF") shows, in vitro, manifesting a regenerative activity on nerve cells of senile animals because NGF has an activity for elongating neurite and regulating aproduction of aneurotransmitter [("Age," Vol. 8, page 19 (1985)]. On the other hand, it is known that the PC 12 cells which are the cells of the strain produced by cloning a species of brown cells of murine adrenal medulla, are caused by addition of NGF to cease propagation and succumb to differentiation into sympathetic nerve-like cells having neurite. Since the NGF has these activities, this has been drawn attention as an antidemential pharmaceutical compositions in recent years. It has been studied that fibroblast growth factor or Interleukin 6 etc. besides NGF induces the growth of neurite by using these cell. Further also, recently, it has shown that SUTAROSUPORIN of a low molecular substance likewise induce elongation of neurite ["Neurochemistry," Vol. 26, pp. 200-220 (1987)].
Since SUTAROSUPORIN mentioned above is a low molecular substance, which differs from NGF, the development for medical use is expected. However, this is not utilized at the present time because of a strong toxicity.
Recently, the physiologically active substance NK 175203 produced by the microorganism of Streptomyces sp. NK 175203 (FERM BP-4372) has been found to have an activity for inducing elongation of neurite (WO 95/31992).
The physiologically active substance NK 175203 (hereinafter referred to as "cystacyclin") is expected to develop into medicine because it is a low molecular compound manifesting low toxicity. But the product amount is only a little because it is produced by the microorganism. Thus, there has been demanded for supply of a low molecular compound obtained by chemical synthesis, which has low toxicity and has a strong activity for promoting induction of neurite.